Cable communications systems and cable devices use a wide range of frequencies to communicate various types of data and/or signals over coax cable. FIG. 1 illustrates an exemplary frequency allocation 100 which may be used in a convention cable system. As illustrated, the exemplary frequency band extends from 0 MHz to 860 MHz.
The low frequency range 0 to 10 MHz is generally left unused in cable systems due to interference from a variety of devices including garage door openers, wireless alarm system signals, etc.
The 10 MHz to 40 MHz frequency band shown in FIG. 1 is often used for, e.g., dedicated to, upstream communications, e.g., data or other communications from a device such as a set top box, via a coax cable network to a device, e.g., a cable modem termination system located at a hubsite or headend. A crossover filter is sometimes used between 42 and 50 MHz in which case these frequencies may be unusable.
Above 50 MHz the communications band shown in FIG. 1 is used for a variety of different types of downstream signals used to communicate information and/or content from a network headend to a customer premise device, e.g., STB located at a customer premise.
A small gap or guard band may exist between the upstream and downstream bands. Thus in the FIG. 1 example the downstream content delivery band is shown corresponding as corresponding to the 50-860 MHz band.
The downstream content may include, for example, analog program content such as broadcast TV programs, broadcast digital program content, switched digital video content, on demand content which may be IP video content and/or unicast data, e.g., downstream Internet traffic data and/or other types of signals.
It should be appreciated that the frequency bands used by cellular communications networks normally range from 700 to 800 MHz. Filters and shielding have until recently proven reasonably successful from protecting cable network communications from radio interference from cellular communications devices, e.g., CDMA or GSM devices. Such interference maybe heard, for example, when a cell phone is near a radio and the interference causes clicking or other noise sounds that are sometimes heard in the audio output of the radio. In the case of communications systems, the effect of the interference is often communications errors which can reduce the reliability of a communications channel.
Over time, cellular systems have been called on to communicate ever greater amounts of traffic whether that be voice traffic or data traffic. In order to support the increasing amounts of traffic many wireless carriers have been switching to what is commonly referred to as 4G systems. LTE (Long Term Evolution) is a common 4G communications standard which is growing in popularity with larger numbers of cell phones and other 4G devices being deployed and purchased at a relatively high rate.
Unfortunately, 4G devices and LTE signals in particular tend to cause interference which is not easily filtered out by many currently deployed cable network devices. Furthermore, the shielding on many cable devices and cables is proving inadequate with respect to protecting from interference from LTE devices.
LTE interference is often caused by a mobile phone or other LTE User Equipment device (UE) being in close proximity to a STB (Set Top Box) or other cable device and being in use, e.g., to transmit or receive data. Accordingly, such interference with respect to an individual customer premise device may not be constant or predictable because it may vary depending on the presence of users with cell phones or other LTE devices, their proximity to a STB or other cable network device and whether or not they are using the LTE device to communicate information. Even when not in active use by the user to transmit traffic, cellular devices can still cause interference since they periodically transmit control information, e.g., status, location and/or other information.
Thus, while interference over the wireless cellular band used for LTE may be a problem, the interference may not be consistent. Simply dropping or blocking use of the frequency channels that may be used for LTE communications would result in a significant loss of bandwidth currently being used for downstream signaling. Such a loss in bandwidth would be particularly undesirable from a commercial standpoint given the ever increasing need for both upstream and downstream communications bandwidth to communicate Internet traffic and/or other type of data to customer premises, e.g., for on demand or other high value services.
In view of the above discussion it should be appreciated that there is a need for methods and apparatus for using frequency bands in a communications system, e.g., a cable network system, which allow for bands subject to cellular network interference to be used in a productive and useful manner.